1. Field of the Invention
The present invention relates generally to trestle constructions and similar structural support apparatus, and more specifically to sawhorses for supporting work surfaces and workpieces, and to leg and cross-brace constructions for these and related supporting structures.
2. Description of the Related Art
Sawhorses traditionally used in the trades and in the home workshop have typically been of simple construction including a horizontal supporting beam with a pair of legs at either end. The legs are commonly secured to the beam at their upper ends, and diverge outward as they project downward from the beam. Horizontal reinforcing elements perpendicular to the plane of the beam, such as braces tying each leg of a pair to the other, are common. Horizontal braces may also run parallel to the beam, tying legs of opposing pairs on the same side of the beam together. In their simplest form, such horizontal braces comprise lengths or panels of wood or metal fastened to the sawhorse's legs with nails or screws. However, when a sawhorse is constructed with permanently-affixed leg braces, it is a rigid structure that is awkward to lift and move, and difficult to store without wasting space.
Storage efficiency and portability are improved in several sawhorse kit-type constructions that permit disassembly of the legs from the beam. One such sawhorse kit comprises a hinged clamp with integral, parallel-projecting legs, wherein the toothed jaws of the clamp are adapted to grip a wooden beam when the legs are splayed outward. One pair of such beam-gripping legs clamped to each end of a two-by-four beam yields the familiar, sturdy, trestle-shaped sawhorse construction. Clamp-on legs of this type can be disengaged from the beam by bringing the legs back into parallel alignment, thus releasing the clamp's jaws from the beam.
While the beam-gripping mechanism of the aforedescribed kit includes legs integral with the hinged clamp, the legs of of other beam-gripping clamp kits are removable. That is, instead of including integral legs, these kits include means for gripping and releasing the individual legs, as well as means for gripping the beam. Thus, when completely disengaged from the legs and the beam, this clamp type permits the sawhorse to be completely broken down into its basic components--four separate legs, two gripping hinges and the beam--for very easy storage.
Despite being technically disassemblable and reassemblable, however, as a practical matter, such kits tend to be difficult to use. One problem is that it can take great deal of force to drive the teeth of such a clamp into the wood of the intended beam; and, keeping the legs at the correct angle to the beam during that process is a challenge. Further, sawhorses constructed from such kits often need additional reinforcement, and the easiest manner of providing that is by addition of the same type of permanent horizontal braces employed on non-collapsible sawhorses, thus eliminating one of the major benefits of such kits.
One type of leg brace that permits a pair of hinged sawhorse legs to be folded into a more storable, portable, parallel orientation is a horizontal strut having a hinged, mid-length joint, wherein each end of the strut has a pivoting connection bound to one of the two legs. Some means for locking the mid-length joint is essential; an over-center locking construction is preferred for ease of use. As the mid-length joint is forced into its over-center position, the legs tied thereto become resistant to splaying farther, and they also become resistant to being collapsed toward each other into their parallel-aligned storage orientation. Such a hinged, locking strut is employed as a brace in kits of the type described above having legs integral with the hinged beam clamp, and in that environment it serves the helpful purpose of keeping the clamp's teeth firmly embedded in the wood of the beam. However, releasing the strut's over-center joint to collapse the legs for storage also loosens the clamp's grip on the beam, thus causing difficulty in the next set-up cycle.
An alternative, partially-collapsible sawhorse construction that potentially has much greater strength and avoids the problems of hinged clamps is comprised of a pair of identical, generally rectangular frame members, wherein the horizontal top portions of the frame members are parallel and hinged to one another. Thus, sawhorses of this construction have a double top beam. Such dual-frame sawhorses are able to be folded into a relatively thin planar configuration for storage. And, although, dual-frame sawhorses may not be as completely collapsible as the clamp-on leg-type sawhorses discussed above, the trade-off in strength and stability is usually worth it. An example of a sawhorse of dual-frame construction is shown in U.S. Pat. No. 5,351,785 issued to DuRapau et al. in 1994. Supplemental horizontal braces parallel to the top beam are not necessary in such a sawhorse because they are an integral portion of each of the identical frame members. But, some kind of horizontal braces transverse to the top beam are essential to keep the two frame members from splaying out too far, or from folding together into the sawhorse's stowing position. Over-center locking struts and other types of ties, straps and brackets have all been used to tie the halves of dual-framed sawhorses together; some, as that in DuRapau et al., include a folding tray as a brace. But, these can be cumbersome to use in that they require hand manipulation of pins, hinges, nuts and bolts, or various other fasteners to set up, and then to fold up, the sawhorse. Further, many have struts, braces or other elements that only permit the sawhorse to be unfolded and assembled from one side. This can be a significant inconvenience when working in tight quarters, or when a user has only one hand free.
Thus, it appears that a need exists for a strong, stable sawhorse design that can be at least partially collapsed. And, it should be easy to use, and to set up and to break down. Further, a need exists for an easy-to-use leg brace or strut for holding splayed legs of sawhorses and other such supporting structures at a fixed distance from one another. Such a brace or strut should be able to be engaged and disengaged easily, but should give strong support and resistance to disengagement when under load.